An Operation System (OS) is provided with a function of virtualizing a storage device. For example, in a Windows (Registered Trademark) server, Virtual Disk Service (VDS) is used. The storage device is also provided with a virtualization function. For example, a Redundant Array of Independent Disks (RAID) device is known.
There is software which associates a RAID device with a VDS used in a Windows server. This software is called VDS Hardware Provider (VDSHP). The VDSHP is mounted in the Windows server such that storage management software which is supported by the Windows OS can set the configuration of the RAID device, such as Logical Unit Number (LUN) or affinity, by using the VDSHP.
The VDS determines VDS_LUN_TYPE as a definition value representing the type of LUN. The definition values do not correspond to RAID levels one to one. The VDSHP stores the definition values of VDS_LUN_TYPE in mapping information in association with the RAID levels which are supported by the RAID device. A RAID device control unit which controls the RAID device sets the LUN in the RAID device with reference to the mapping information.
For example, a case where stripe LUN is set in the RAID device from the server as an example of VDS_LUN_TYPE will be described with reference to FIG. 17. FIG. 17 is a diagram illustrating a case where a stripe LUN is created in the related art. First, in a server 100, storage management software 101 acquires a stripe-designate LUN creation request (a1). When this happens, the storage management software 101 requests a VDSHP 102 to create LUN with VDS_LT_STRIPE, which is one of the definition values of VDS_LUN_TYPE, as a parameter (a2). Then, the VDSHP 102 activates a RAID device control unit 103. Next, the RAID device control unit 103 refers to mapping information 105 stored in a mapping information storage unit 104 (a3) and extracts the RAID level associated with VDS_LT_STRIPE. It is assumed that the RAID level associated with VDS_LT_STRIPE is RAID1+0.
Subsequently, the RAID device control unit 103 issues to a RAID device 200 a LUN creation command with the extracted RAID level, that is, RAID1+0 as a parameter (a4). Thereafter, in the RAID device 200, a RAID configuration information change unit 201 changes RAID configuration information 203 stored in a RAID configuration information storage unit 202 to set LUN on RAID1+0.
A technique is known in which, when VDS is not embedded in the server, mapping information which represents the correspondence relationship between the logical volume of a RAID device and the logical volume of an external storage device is stored in the server, and the external storage device and the RAID device are managed uniformly.
However, the VDS may not support some of the RAID levels. As an example, it is impossible to associate all the RAID levels supported by the RAID device with the definition values of VDS_LUN_TYPE defined by the VDS, thus the VDS does not support the RAID level which cannot be associated with the definition values. That is, in the mapping information, the definition value “VDS_LT_SPAN” of VDS_LUN_TYPE is associated with RAID6, and the definition value “VDS_LT_PARITY” is associated with RAID5. The definition value “VDS_LT_MIRROR” is associated with RAID1, and the definition value “VDS_LT_STRIPE” is associated with RAID1+0. On the other hand, RAID0 or RAID5+0 is not associated with the definition value of VDS_LUN_TYPE, thus the VDS does not support RAID0 or RAID5+0.
As another example, as described above, in the mapping information, the correspondence relationship between the definition values of VDS_LUN_TYPE and the RAID levels is fixed, so that it may be impossible to dynamically change the mapping information. For this reason, when a RAID level is added to the RAID device, it may be impossible to change the mapping information in accordance with the addition of the RAID level. That is, the VDS does not support the added RAID level.    Patent Document 1: Japanese Laid-open Patent Publication No. 2006-65709    Patent Document 2: Japanese Laid-open Patent Publication No. 2003-296154